PPG-51
AKA: Polypropylene Glycol-51, Humectant
Synthetic
Skin Conditioner
Not Clean
Poly[oxy(methyl-1,2-ethanediyl)], .alpha.-hydro-.omega.-hydroxy- (51 mol PO average molar ratio)
CAS #
25322-69-4
Form
Liquid
Functions
Skin Conditioning
A catch-all term for ingredients that improve how skin looks and feels — softer, smoother, more supple. The workhorse behind most moisturizers.
Locks in moisture
Traditional Use
A high-molecular-weight synthetic polypropylene glycol developed in the mid-20th century for use as a humectant and thickening agent in cosmetic formulations.
Skin Types
●all-skin-types
Best For
General
Pregnancy & Breastfeeding Safe
Yes
The paper trail
🔬Peer-reviewednone on file
⚖️Regulatory1 listing →
🛡️Safety-assessed2 reviews →
Counts, not a verdict. A listing isn't a study. The trail, you decide.
Verified Jun 2026
Data: CosIng · EWG · CIR